STK4192 datasheet - Datasheet Catalog

STK4192IIIn an actual application where a music signal is used, it is impractical to estimate the power dissipation based on the continuoussignal as shown above, because too large a heat sink must be used. It is reasonable to estimate the power dissipationas 1/10 Po max. (EIAJ).That is, Pd = 43W at 8Ω, Pd = 55W at 4ΩThermal resistance θc-a of a heat sink for this IC power dissipation (Pd) is fixed under conditions 1 and 2 shown below.Condition 1: Tc = Pd × θc-a + Ta ≤ 125°C............................................... (1)where Ta : Specified ambient temperatureTc : Operating substrate temperatureCondition 2: Tj= Pd × (θc-a) + Pd/4 × (θj-c) + Ta ≤ 150°C..................... (2)where Tj : Junction temperature of power transistorAssuming that the power dissipation is shared equally among the four power transistors (2 channels × 2), thermal resistanceθj-c is 1.8°C/W andPd × (θc-a + 1.8/4) + Ta ≤ 150°C........................................ (3)Thermal resistance θc-a of a heat sink must satisfy inequalities(1) and (3).Figure 3 shows the relation between Pd and θc-a givenfrom (1) and (3) with Ta as a parameter.[Example] The thermal resistance of a heat sink isobtained when the ambient temperature specifiedfor a stereo amplifier is 50°C.Assuming V CC = ±35V, R L = 8Ω, V CC = ±31V, R L = 4Ω,R L = 8Ω : Pd1 = 43W at 1/10 Po max.R L = 4Ω : Pd2 = 55W at 1/10 Po max.The thermal resistance of a heat sink isobtained from Figure 3.R L = 8Ω : θc-a1 = 1.75°C/WR L = 4Ω : θc-a2 = 1.35°C/WTj when a heat sink is used is obtained from(3).R L = 8Ω : Tj = 144.6°CR L = 4Ω : Tj = 149°CThermal resistance of heat sink, θc-a - °C/WIC Power dissipation, Pd - WFigure 3. STK4192II θc-a – Pd■■■No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclearpower control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury,death or property loss.Anyone purchasing any products described or contained herein for an above-mentioned use shall:➀ Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all theirofficers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associatedwith such use:➁ Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO.,LTD., its affiliates, subsidiaries and distributors or any of their officers and employees, jointly or severally.Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYObelieves information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements ofintellectual property rights or other rights of third parties.This catalog provides information as of July, 1997. Specifications and information herein are subject to change without notice.No. 2305—8/8